I PAT

I PAT is the lettering of a notable formula put forward to describe the impact of human activity on the environment.

:I = P × A × T

In words:

:Human Impact (I) on the environment equals the product of population (P), affluence (A: consumption per capita) and technology (T: environmental impact per unit of consumption).

This describes how our growing population, affluence, and technology contribute toward our environmental impact.

The equation was developed in the 1970's during the course of a debate between Barry Commoner, Paul R. Ehrlich and John Holdren. Commoner argued that environmental impacts in the United States were caused primarily by changes in its production technology following World War II, while Ehrlich and Holdren argued that all three factors were important and emphasized in particular the role of population growth. [O'Neill et al. 2004. Population, Greenhouse Gas Emissions and Climate Change. Essay in book: Lutz W. et al (editors). 2004. "The End of Population Growth in the 21st Century" London: Earthscan]

The equation aids in understanding the various factors affecting human impacts on the environment. The technology factor can be confusing, as technology can be used both to save resources, and to exploit them further. However, generally technology is used to harness energy and increases impacts (ie, cars, pesticides, etc.).

ee also

* Carrying capacity
* Ecological footprint
* Carbon footprint
* Water footprint

References